I think each quilt "speaks" for itself. Many designs are made to use a lot of quilting, like if there are big empty blocks separating pieced ones. There a quilter can demonstrate her abilities. Other quilts have such complicated piecing that minimal quilting is required to concentrate on the piecing. I believe that if the quilt is well made, you look at it and notice the piecing, and then have your eye drawn to the quilting, unless is a whole cloth, of course.
Let's not forget that quilting is an art, no matter if it is done on a domestic or a long arm. It is almost like drawing, but harder. What I frown upon is long arm quilted items done with computarized machines, where all you do is mark the boundaries and go to lunch, competing in the same category as a regular long armer, who made hers free hand or marked.
I always prefer to quilt rather than piecing, but I do it on my domestic machine.